The Santa Cruz River that once flowed through Tucson, Arizona is today a sad mirage of a river. Except for brief periods following heavy rainfall, it is bone dry. The cottonwood and willow trees that once lined its banks have died, and the profusion of birds and wildlife recorded by early settlers are nowhere to be seen. The river is dead. What happened? Where did the water go. As Robert Glennon explains in Water Follies, what killed...